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Microtus drummondii

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Western Meadow Vole
(Microtus drummondii)
Range
Taxonomic classification
Order:Rodentia
Suborder:Supramyomorpha
Infraorder:Myomorphi
Superfamily:Muroidea
Family:Cricetidae
Subfamily:Arvicolinae
Tribe:Microtini
Genus:Microtus
Subgenus:Pitymys
Binomial details
Microtus drummondii (Audubon & Bachman, 1854)

Jackson & Cook (2020) proposed that the eastern clade of Microtus pennsylvanicus be referred to as Microtus pennsylvanicus (Ord 1815), the western clade as Microtus drummondii (Audubon and Bachman 1853), and the coastal Florida clade as Microtus dukecampbelli (Woods, Post, and Kilpatrick 1982). The work by Jackson & Cook (2020) is based on a cytochrome b (Cytb) analysis and the range map to the right represents the hypothesized range limit of Microtus drummondii. Further studies will be needed to fully understand new species boundaries.

Description

The following description is from Armstrong et al. (2010), describing Microtus pennsylvanicus in Colorado, before the species was split by Jackson & Cook (2020): "This is a fairly large, dark-colored vole with a gray to silvery belly. Dorsal color is usually dark gray-brown to chestnut. The tail is bicolored and scantily haired. The tail is longer than that of most prairie voles [Microtus ochrogaster] but relatively shorter than in the long-tailed vole [Microtus longicaudus]. The ears are rounded and inconspicuous beneath the long fur on the head. Younger animals are typically darker in color than are older individuals."

The color of the pelage aroung the scrotum in reproductive males ranges from silvery-gray to rusty-brown.

External measurements

Length measurements are in millimeters (mm) and weight measurements are in grams (g), unless stated otherwise. If available, the sample size (n=) is provided. If a range is not provided and n= is not given, then the listed measurement represents an average.

Part of range Reference Total length Tail length Hindfoot length Ear length Mass
Colorado Armstrong et al. (2010) 155–192 35–67 20–24 11–18 35–75
Minnesota Hazard (1982) 137–171 32–43 17–20 10–15 31.3–52.2
North Dakota Seabloom et al. (2020) 155 39 19 12 40


Color variation

This section shows some of the color variation present in Microtus drummondii. The location is provided for reference only. The individual shown does not necessarily represent the only color variant within the local population.

  • Alaska, Denali Borough
    Alaska, Denali Borough
  • North Dakota, Morton County
    North Dakota, Morton County
  • North Dakota, Stutsman County
    North Dakota, Stutsman County
  • North Dakota, Stutsman County
    North Dakota, Stutsman County
  • Wyoming, Park County
    Wyoming, Park County

Skull

The following characters identified by Naughton (2012) are for M. pennsylvanicus, before the species was split by Jackson & Cook (2020): "(a) M2 has 5 closed loops (3 triangles and an anterior loop plus a rounded, closed lingual posterior loop which may resemble an incipient 5th triangle in some individuals); (b) M3 usually has 3 re-entrant angles on either side but this trait is variable especially on the labial side, where a 4th incipient angle may occur; c) triangles (arrows) on m1 are narrow and usually sharply pointed, especially on lingual side; d) m1 has 4 and sometimes 5 lingual and 4 labial re-entrant angles."

  • Dorsal view of the skull of Microtus drummondii.
  • Lateral view of the skull of Microtus drummondii.
  • Ventral view of the skull of Microtus drummondii.
  • Lower jaw of Microtus drummondii.
  • Upper incisors of Microtus drummondii.
  • Enamel pattern of Microtus drummondii. The left pair are the upper molars (top to bottom are M1, M2, M3) and right pair are the lower molars (top to bottom are m1, m2, m3).
  • Underside of the skull of Microtus drummondii, showing the upper molars (M1-M3). Use Naughton's (2012) description above for M2 and M3.

Similar species

Comparison with Clethrionomys

Clethrionomys gapperi and Clethrionomys rutilus are easily distinguished from Microtus drummondii by the broad, reddish mid-dorsal stripe extending from forehead to tail.

  • Dorsal view of the Southern Red-backed Vole (Clethrionomys gapperi) showing the broad, reddish mid-dorsal stripe extending from forehead to tail.
  • Dorsal view of Northern Red-backed Vole (Clethrionomys rutilus) showing the broad, reddish mid-dorsal stripe extending from forehead to tail.
  • Dorsal view of Microtus drummondii

Comparison with Microtus abbreviatus

In the field, Microtus abbreviatus can be distinguished from Microtus drummondii by its much shorter tail.

Comparison with Microtus longicaudus

In the field, Microtus longicaudus can be distinguished from Microtus drummondii by its much longer tail. The tail of M. longicaudus is greater than one-third the length of the head and body.

Comparison with Microtus montanus

Comparison with Microtus ochrogaster

From Sera & Early (2003): "M. montanus has 3 closed triangles on M3 and 8 mammae, whereas the potentially sympatric M. ochrogaster has only 2 closed triangles on M3 and 6 mammae."

Comparison with Microtus pennsylvanicus

Jackson & Cook (2020) proposed that the eastern clade of Microtus pennsylvanicus be referred to as Microtus pennsylvanicus (Ord 1815) and the western clade as Microtus drummondii (Audubon and Bachman 1853). The ranges published by Jackson & Cook (2020) represent hypothesized range limits of each clade based on a cytochrome b (Cytb) analysis. Further studies will be needed to fully understand new species boundaries. In areas where these two species may co-occur, it may not currently be possible to distinguish them using morphological characters.

  • Microtus drummondii
  • Eastern Meadow Vole (Microtus pennsylvanicus)
  • Range of Microtus drummondii based on Jackson & Cook (2020).
  • Range of Microtus pennsylvanicus based on Jackson & Cook (2020).

Comparison with Microtus richardsoni

In the field, Micortus richardsoni can be distinguished from Microtus drummondii by its much larger size. Additionally, the fur on the underparts of M. richardsoni is plumbeous, with white or silvery-white wash, instead of pale buff, grey, or silvery in M. drummondii.

  • Microtus drummondii
  • Ventral view of Microtus drummondii. The color of the underparts ranges from pale buff to grey or silvery.
  • North American Water Vole (Microtus richardsoni). Note the size of the scale bar. This is the largest vole in North America.
  • Ventral view of the North American Water Vole (Microtus richardsoni). The underparts are plumbeous with white or silvery-white wash.

Comparison with Phenacomys intermedius

References

Armstrong DM, Fitzgerald JP, Meaney CA. 2010. Mammals of Colorado, Second Edition. Denver (CO, USA): University Press of Colorado.

Hazard EB. 1982. The mammals of Minnesota. Minneapolis (MN, USA): University of Minnesota Press.

Jackson DJ, Cook JA. 2020. A precarious future for distinctive peripheral populations of meadow voles (Microtus pennsylvanicus). Journal of Mammalogy 101(1):36-51.

Naughton D. 2012. The natural history of Canadian mammals. Toronto (ON, CA): University of Toronto Press.

Seabloom R, Hoganson JW, Jensen WF. 2020. The mammals of North Dakota. Fargo (ND, USA): North Dakota State University Press.

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